Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Operating, consolidated variable interest entities	$ 281,960	$ 265,138
Accumulated depreciation and amortization, consolidated variable interest entities	24,714	19,086
Debt issuance costs, accumulated amortization	11,653	9,535
Mortgages payable, consolidated variable interest entities	$ 188,189	$ 202,782
Preferred shares, authorized	15,000,000	15,000,000
Preferred shares, par value	$ 0.01	$ 0.01
Preferred Shares, percentage	5.417%	5.417%
Preferred Shares, 5.417% Series 1 Cumulative Convertible liquidation preference	$ 25	$ 25
Preferred shares, shares issued	399,896	399,896
Preferred shares, shares outstanding	399,896	399,896
Common shares of beneficial interest, par value	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized	100,000,000	100,000,000
Common shares of beneficial interest, shares issued	68,128,519	66,701,422
Common shares of beneficial interest, shares outstanding	68,128,519	66,701,422